Amicus
Therapeutics (Nasdaq: FOLD) and GlaxoSmithKline plc (NYSE: GSK) today announced the
6-month primary treatment period results from the first Phase 3 global
registration study (Study 011) of investigational oral migalastat HCl
monotherapy in males and females with Fabry disease who had genetic mutations
identified as amenable to migalastat HCl in a cell-based assay. Study 011
randomized a total of 67 patients to receive oral migalastat HCl 150 mg or
placebo on an every-other-day (QOD) dosing schedule during a 6-month,
double-blind primary treatment period.

Reduction of GL-3 Substrate in Kidney Interstitial Capillaries:

Globotriaosylceramide (GL-3) is the lipid substrate that accumulates in
tissues of patients with Fabry disease, most notably in the kidney. GL-3
clearance from the kidney interstitial capillaries has been used as a marker
of treatment effect in Fabry disease. The pre-designated primary endpoint of
Study 011 was a responder analysis evaluating the number of patients who
demonstrated a 50% or greater reduction in kidney interstitial capillary GL-3
after 6 months of treatment with migalastat HCl compared to placebo. During a
6-month open label follow-up period all patients received migalastat HCl. The
FDA has also indicated that it will consider the 12-month efficacy and safety
data from Study 011. The paired kidney biopsies from baseline and month 6 were
assessed by histological scoring using the published, quantitative Barisoni
Lipid Inclusion Scoring System with Virtual Microscopy (BLISS-VM).^1 This
methodology will also be utilized for the evaluation of the kidney biopsies at
month 12. Amicus and GSK remain blinded to the 12-month data.

In Study 011 patients with evaluable baseline biopsies, 13/32 (41%) in the
migalastat HCl treatment group demonstrated a 50% or greater reduction in
kidney interstitial capillary GL-3 after 6 months of study treatment versus
9/32 (28%) in the placebo group. This difference did not achieve statistical
significance (p=0.3) according to the pre-specified primary endpoint analysis.

In addition to the binary responder analysis reported above, a pre-specified
secondary analysis assessing the absolute percent change in kidney
interstitial capillary GL-3 from baseline to month 6 was performed. Taken
alone this analysis showed a median reduction of 41% in the migalastat HCl
group versus a median reduction of 6% in the placebo group (p=0.093).

To date, no drug-related serious adverse events have been observed. The most
common treatment emergent adverse events occurring in 10% or more of subjects
were (migalastat; placebo, respectively): headache (35%; 21%); fatigue (12%;
12%); nausea (12%; 9%); nasopharyngitis, or inflammation of the nose and
throat (15%; 6%); and parasthesia, or tingling sensation of the skin (9%;
12%). The 4 dropouts in this portion of the study were deemed by the
investigators to be unrelated to study medication.

The 6-month secondary endpoints in Study 011 continue to be analyzed and will
be presented at the Lysosomal Disease Network WORLD Symposium (LDN WORLD), to
be held February 12-15, 2013, in Orlando, Florida. Secondary endpoints include
urine GL-3 and renal function (iohexol GFR, eGFR and 24-hour urine protein).